Dash-pot.



A. u. JJIVERMORE.

DASH POT. APPLICATION FILED JUNE 13, 1911. 1,039,555. Patented :Sept.24, 1912.

2 SHEETS-SHEET 2.

FIG. 3

WITNESSES [NVEN TOR.

yf'/' 137 am A. G. LIVERMURE.

DASH POT.

APPLICATION FILED JUNE 13, 1011.

Patented Sept. 24, 1912.

2 BKEBTBSHEET 1.

[NV NTOR. .4. 151

WITNESSES 06 ATTORNE s'rnrns PATENT-omen.

ARTHUR e; IIVEBMOBE, or nncnwoon PARK, rmmsx'nvninn, nssmnori To win:

UNION- swrrcn a stoma. company, or swrssvam', Psmsiznvmm, A oonro-BATION OF PENNSYLVANIA.

nAsn-re'r.

Specification of Letters Patent.

Patented sepa ze, 191s,

Application filed June 13, 1911. Serial 1T0. 682,831.

To all whom it nuiy ing at Edgewood Park, in the .county of Alleghenyand State of Pennsylvania, have invented certain new and usefulImprovements in Dash-Pots, of which the following is a specification.

My invention relates to bufiing devices for railway signals, andparticularly to air bufiers for railwaysignals of the semaphore typehaving a plurality of positions of indication.

I will describe one form of air bufier embodying my invention, and thenpoint out the novel features thereof in claims.

In the accompanyingdrawings, Figures 1, 2 and, 3 are views showing asemaphore signal in three different positions of indication, and showinga buffing device embodying my invention with its parts in the threecorresponding posit-ions. Fig. 4. is a vertical sectional View showingin detail the form of buifing device illustrated in Figs. 1, 2 and 3.

Similar reference characters refer to similar parts throughout theseveral views.

Referring to Fig'sl'1,,2 and 3 of the accompanyingdrawings, A designatesa railway semaphore signal, and B a mechanism for moving it. Thesemaphore signal comprises as usual a-blade 5-and a spectacle casting 6.Thesemaphore is suitably fixed on a shaft 7 ,and when free to movealways 35 assumes a'horizontal position of'the blade under theinfluenceof gravity on the. blade and on the spectacle casting. In the drawings Ihave shown the semaphore as being adapted for movement from itshorizontal position upwardly to two other'positions of indication, butit may equally'wellbe adapted for movement from its horizontal positiondownwardly to other positions of mdication. These arrangements arezwellunder stood by those skilled in the art and involve merely mechanicalchanges which need not be explainedherein. The operating mechanism B ashere shown comprisesan arm 8 pivoted at one end and provided at itsother end. with a fork 9 pivoted to the arm and adapted to beheldarigidwith: the arm by means of an electromagnet 30, and suitable apparauscarried f hy the arm. .10 and 13 designate-chains driven by, 'a motor11, which-- chains are provided with projections ar: ranged to engagethe fork 9 to raise the arm.. Stationary supports 14 and 15 are alsoprovided to engage with the fork to hold the arm in the positions towhich it has been moved. The arm 8 is connected with the semaphore bymeans of a rod 12 and a suitable crank secured to the semaphore shaft 7An operating mechanism of the general type such as I have herein shownis shown and described in United States Letters Patent No. 611943 issuedon October 4, 1898', to, J.- G. Schreuder. It is understood, however,

that I do not wish to limit myself to any specific type'of operatingmechanism.

As here shown the semaphore A. is moved by the mechanism B from thehorizontal position, (usually the danger position) to an inclinedposition (usually the can- During the return movements of the semaphore,it is desirable that the momentum of the parts should be checked beforethey reach the positions corresponding tothe tin clined andhorizontalpositions of the se'r'na-- phore. This I accomplish by meansof a bufiing device embodying my invention, one form of which I will nowdescribe.

. A buflin comprises hut one cylinder-and but one; piston havingrelative movements, and 'this buffing device serves to cushion themoving parts as they approach both the inclinedv and horizontalpositions ofthe semaphore. As the parts approach the inclined position,-

the piston is substantially -midway' of its stroke through the cylinder,hence the compression of the air inst-he cylinder bythe piston might notat this point be sufficient to eflectivelycushion the movement of theparts. To secure the desired cushioning effect atthe inclined position,I so arrange. the butler as to permit the piston to create a partialvacuum behind itself duringv that portion of'itsstroke corresponding tothe movement of the semaphore: from vertical:

t9 inclined positions. By means-of this partral vacuum or by. means.of-the partial vacuum combined with the compression of the air on theother side-"of the pistom. I

effectively cushion themoving parts as they device embodying myinvention.

tion position) and to a substantially vertical position (usually theclear ?'position').

of the cylinder, and the partia approach the inclined positio phore.During the moveme V I phore from the inclined to th -horizont-a-lposition, the piston is approach" hind the piston is not usuallynecessary during this portion of the stroke, for the reason that theparts can then be effective] cush ioned by the compression of air inrent of mechanism at 31 and the piston is opera-' tivcly connected withthe arm 8 by means of a piston rod 18 and a yoke 32. It is understood,however, that this arrangement may equally well be reversed, the pistonbeing fixed and the cylinder being operatively I connected with the arm8. The cylinder is closed at both ends, being provided at its upper endwith a head 20 which carries a stufiing box 21 through which passes thepiston rod 18.

22 designates a check valve at the upper end of the cylinder, here shownas compris-v ing a ball 23 resting inia suitable conical seat. Thisvalve permits the air to be freely driven out of the upper part ofthecylinder during the. upward movement of the piston, but prevents theflow of air into the upper part of the cylinder during the downwardmovement of the piston. Adjacent the lower end of the cylinder is asimilar check valve 2 1 here shown as comprising a ball 25 which permitsair to flow freely into the lower ortion. of the cylinder during theupwar movement of the piston, but which prevents the outflow of the airunder comvpression in the lower'portion of the cylinder during thedownward movement of the piston.

28 designates an adjustable relief valve by means of which the outflowof air from the lower portion of the cylinder during the downward orcompression stroke may be regulated to avoid complete stoppage of themoving parts and yet to provide the desired cushioning effect. Ifdesirable, a similar adjustable valve 29 may be provided at'the upperendof theited influx of air suction stroke of the piston, although theleaka e of'air through the stufling will usual y render this reliefvalve unnecessary. It will be clear'that with a as thus 'far described,the pressure 0 the air rg'linder to permit a lim uring the downward or.

device inthe cylinder-above the piston will be reduced below.atmospheric (pressure as soon as the piston begins its ownward movement,and that thls pressure will constantly become lower-as the piston movesfarther away from theupper head. The first part of the movement of thesemaphore from its vertical position will therefore be comparativelyrapid, but the momentum of the parts willbe checked by the partialvacuum above the piston as the semaphore approaches its inclinedposition, thereby providing the desired cushioning effect at this point.The cushioning eifect is assisted, as hereinbefore mentioned, by thecompression of air ahead of the piston.

If no meanswere provided for relieving the partial vacuum behind thepiston after the semaphore has reached the inclined position, it isevident that the entire move ment from the inclined to the horizontalposition would be extremely slow. It is desirable however, that theearly part of this movement should be rapid, and that the momentum ofthe moving parts should be checked only as thesemaphore approaches itshorizontalvposition. In order to relieve the partial vacuum I preferablyprovide a rod secured to the piston and passing out through a stuflingbox in one end of the cylinder, which rod is provided with air passagesso arranged as to connect the end of the cylinder in which the partialvacuum exists with the atmosphere during the move ment of the semaphorebetween its inclined and horizontal positions. As shown in Fig.

4 I em loy the piston rod 18 for this pur pose, a thou h I do not wishto be limited 7 with a longitudinal passage 19 which communicates withthe atmosphereat 27 where the piston rod unites with the yoke 32.

26 designates a transverse opening through thewall of the rod 18communicating with .thepassage 19. This transverse opening is so locatedas to be within the cylinder while the semaphore is between itshorizontal and inclined positions, but to be opposite the stufling box21 or inthe outside alr while the semaphore is between its inclined andvertical positions. 7

It will be evident from the foregoing explanation that after thesemaphore has reached the inclined position on its movementtowardhorizontal the end of the cylinder'in which the partial vacuumexists is" opened to atmosphere and that from theinclined to thehorizontal position the cush-T ioriing efiect is obtained solely bythe-com-' presslon of air ahead of the piston. 4 Although I have hereinshown and described only one form of air bufier embodying my invention,it is understood that various modifications may be made therein Withinthe scope of the appended claims without departing from the spirit andscope of my invention.

. Having thus I claim is': V

1. A butiing device comprising a cylinder and a piston having relativemovement, the said movement in one direction being retarded throughoutan entire strokeby the compression of air on one side'of the piston andthrough a portion of the said stroke by a partial vacuum created on theother side of the piston by the said movement. 7

2. A'bufling device comprising a cylinder and a piston having relativemovement, the said movement in one direction being retarded throughoutthe stroke by-the compression of air onone side ofthe piston and througha portion of the strokeby the par tial vacuum created on the other sideof the piston by the said movement, and means for relieving the partialvacuum. during theremainder of the said stroke.

3. A bufling device comprising a cylinder and a piston having relativemovements, the cylinder being closed at both ends to permit the relativemovement to create apartial vacuum on one side of the piston during aportion of on the other side of the piston during the entire stroke, andmeans for opening the cylinder on the vacuum side of the piston toatmosphere aztter the said portion of the said stroke has beencompleted.

described my invention, what 4. A buiiing devicecomprising cylinder anda piston having relative movements, the

cylinder being closed at both ends to permit the relative movement inone direction to create a partial vacuum-on one side of the pistonduring a portion of a stroke and a compression of air'o-nthe other sideof the piston during the entire stroke, means for opening the cylinderon the vacuum side of the piston to atmosphere after the said portion ofthe said stroke has been completed,

and check valves in each end of the cylinder to permit a free relativemovement in the opposite direction.

5. A bufiing device comprising a cylinder and a piston having relativemovements, the cylinder being closed at both ends to'permit the relativemovement in one direction to create a partial vacuum on one side of thepiston during'a portion of a stroke and a compression of air on theother piston during the entire stroke, means for opening the cylinder onthe vacuum side of the piston-to atmosphere after thesaid portion of thesaid stroke has been completed,

and a release valve in the cylinder onthe compression side of the pistonto permit a slow outflow of air during the movement in the saiddirection.

a stroke and a compressionof air side of the 6.-A buflin devicecomprising a cylinder and a pistonhaving relative movements, thecylinder being, closed at both ends to permit the relative movement inone direction to create a partial vacuum on one side of the pistonduring a portion ofa stroke and a compression of air on the other sideof the piston during the entire stroke, means for opening the cylinderon the vacuum side of the piston-to atmosphere after the said portion ofthe said stroke has been completed, and-a release valve in the cylinderon the vacuum side of, the piston to'permit a slow inflow of air duringthe movement in the said direction. 1

Y 7. A buflin device-comprising a cylinder and a piston aving relativemovements, the

cylinder being-closed at both ends, a rod connected with the piston andpassing through one end of the cylinder, a longitudinal .passage in saidrod open to atmosphere at all times, and an opening through the wall-ofthe rod communicating with the passage and :located to be outside of thecylinder during a portion of the relative movement andin side of thecylinder. during the remainder of the movement.-

8. Abulfing device comprising a cylinder and a piston having relativemovements, the cylinder being closed atone end, a'rod connected with thepiston and passing through the-closed end of the cylinder, alongitudinal passagethrough said rod open to atmo-s phere at all times,and an opening through the wall of-the rod communicating with the saidpassage and located to be ithin'the closed end of the cylinder during aportion of the relative movement and outside of t e saidclosed endduring-the i'emainder of t e relative movement.

9. A bufiing device comprising a cylinder and a piston having relativemovement, the

cylinder belng closed at" both ends, a rod connected with the piston andpassing through one end.ofthe cylinder, and a passage throughithe rodone end of which is open to the atmosphere at all times and the otherend of which is within the cylinder during a portion of the relativemovement and without thecylinder during the remainder of the relativemovement.

10. A bufling device comprising a cylinder and a piston having relativemovement, the cylinder being closed at both ends to cushion the relativemovement during a portion of a stroke by a partial vacuum and during theentire stroke by compression.

11. A bufiing device comprising a cylinder and a piston havingrelativemovement, the said relative movement in one direction being retardedthroughout the entire stroke .by compression on one side of the piston,and:

through substantially the first half of said stroke by other sideof thepiston by said-strove he partial vacuum created'on'the throughsubstantially the'first half of said.

7 said stroke.

comprised in said rod for relieving the said v der and .a piston havingrelative movement,

the cylinder being closed at both ends, a rod connected :with the pistonand, passing through one of the said closed ends, the

ment, and means for relieving said partial vacuum during substantiallythe last half of said stroke.

12. A butting device comprising a cylinder and a piston having relativemovement, the said relative movement in one direction being retardedthroughout the entire stroke by compression on one side of the piston,and

stroke by the partial vacuum created on the other side of the piston bythe said movement, and means for opening the vacuum side of the cylinderto atmosphere during substantially the last half of said stroke.

13. A. buffing deviceecomprising a cylinder and a piston having relativemovement, the cylinder being closed at one end, a rod connected WllZ-l1the piston and passing through the closed end, the relative movement inone direction being retarded through a portion'of the stroke by thepartial vacuum created between the piston and the closed end by suchrelative movement, and means partial vacuum during theremainder of the14. A butting device comprising a cylin the cylinder being closed at oneend, a rod connected with the piston and passing through the. closedend, the relative movement in one direction being retarded through aportion of the stroke by the partial vacuum created between the pistonand the closed end by such relative movement, and means comprised insaid rod for openingthe said closed end of the cylinder to atmosphereduring the remainder of the stroke. I

- 15; A butfing device comprisinga cylinder and a' piston havingrelative movement,

relative movement in one direction being retarded throughout the entirestroke by the compression on one side of the piston'and through thefirst portion of said stroke by I the partial vacuum created on theother side of the piston by the said relative movement,

through a portion of the said stroke by the partial vacuum created ontheother side of the piston by the said movement, and means for opening thecylinder on the vacuum side of the piston to atmosphere during the remainder of the said stroke.

17. In combination, a movable device adapted to move from. one positionto a second position and to continue the movement inlthe'same directionfrom saidsecond position to a third position, a buffing device forcushioning the movement as the said 'movable device approaches the saidsecond osition and the said third position, said ufiing devicecomprising a cylinder and a 'piston having relative movement one ofwhich is connected with the movable device,

the said relative movement being cushioned throughout the entire strokeof the movable device by the compression on one side of the piston andthrough the portion of the stroke of the movable device from the firstto the second position by the partial vacuum cre-' ated on the 1 otherside of the piston bythe said relative movement, and means for relievingthe partial vacuum during the move- -ment from the second to the thirdposition.

In testimony "whereof I afiix my signature in presence of twowitnesses.-

Witnesses:

, -A. L. VENGILL, P. F. WILLARD.

ARTHUR o. LIVERMORE,

